1. Field of the Invention
This invention relates, generally, to miniature electrical vehicles which ride on a track that includes electric power rails and, more particularly, to an improved electric motor arrangement for such a vehicle with an advantageous magnet structure which provides magnetic attraction between the vehicle and the power rails so as to increase the traction of the vehicle against the track.
2. Prior Art
The prior art includes a plurality of electrically powered miniature vehicles usually in the form of automobile race cars, which ride on a track. The track is usually fabricated of a type of plastic and includes at least a pair of power rails embedded in the track. The power rails are electrically conductive, typically of metal such as brass or the like, and are used to provide electrical power to the vehicle.
Miniature vehicles of this general type have been successfully manufactured and marketed in the past. These vehicles include magnets which form the stator of the electrical motor. The electrical power is supplied to the rotor or armature of the motor via a commutator which receives electrical power from the rails via contacts or "shoes" mounted on the vehicle. The armature is typically positioned horizontally between the North/South poles of the magnets.
All other known models employ a motor design wherein the North/South axis orientation of the magnets is horizontal thus limiting the magnetic down force available over the rails. Nevertheless, designers are continuously striving to produce such vehicles capable of quicker acceleration and higher speeds. One problem in the development of such a high speed vehicle is insufficient traction force between the wheels of the vehicle and the track. That is, when an operator applies an electrical signal to produce acceleration or higher speed by the vehicle, the wheels tend to spin needlessly on attempted acceleration and/or the vehicle tends to spinout on curves. The relatively low traction results largely from the rather insubstantial weight of the miniature electrical vehicles. However, merely increasing the weight of the vehicle does not solve the problem because a vehicle with a larger mass will accelerate more slowly unless a stronger motor is provided, which further increases mass and size.
Typically, in attempting to improve the operation of the car, the weight of the car prevents further improvements. That is, as weight is reduced, traction is reduced. On the other hand, as weight is increased, acceleration and speed are reduced.
Because a substantial portion of the weight of the car is represented by to the relatively bulky magnets required by the relatively large diameter armature, various magnet designs have been explored. These have included the use of the magnets to provide attraction to the power rails, flux adjacent to the magnets, and the like. However, it has not been possible to reduce the size of the motor to any substantial extent in order to reduce its weight, because this would reduce the normal force exerted on the track and would merely re-implement the problems which the arrangement had solved.
What is needed is a substantial, further increase in the normal force of the vehicle against the track so that the weight of the vehicle is reduced without losing traction or so that normal force and traction can be increased without an increase in the mass of the vehicle.